Chlorophyll sensitized BiVO4 as photoanode for solar water splitting and CO2 conversion

Abstract Converting solar energy into valuable hydrogen and hydrocarbon fuels through photoelectrocatalytic water splitting and CO 2 reduction is highly promising in addressing the growing demand for renewable and clean energy resources. However, the solar-to-fuel conversion efficiency is still very low due to limited light absorption and rapid bulk recombination of charge carriers. In this work, we present chlorophyll (Chl) and its derivative sodium copper chlorophyllin (ChlCuNa), as dye sensitizers, modified BiVO 4 to improve the photoelectrochemical (PEC) performance. The photocurrent of BiVO 4 is surprisingly decreased after a direct sensitization of Chl while the sensitization of ChlCuNa obviously enhances photocurrent of BiVO 4 electrodes by improved surface hydrophilicity and extended light absorption. ChlCuNa-sensitized BiVO 4 achieves an improved H 2 evolution rate of 5.43 μmol h −1  cm −2 in water splitting and an enhanced HCOOH production rate of 2.15 μmol h −1  cm −2 in CO 2 PEC reduction, which are 1.9 times and 2.4 times higher than pristine BiVO 4 , respectively. It is suggested that the derivative ChlCuNa is a more effective sensitizer for solar-to-fuel energy conversion and CO 2 utilization than Chl.